During refinishing or resurfacing of a rotating workpiece mounted on a rotatable shaft, a workpiece and the shaft may be subjected to a variety of forces and phenomena. In general, forces due to rotation and gravity tend to preclude uniform rotation of a rotating shaft and a rotating workpiece in a single, unvarying plane of rotation. If the workpiece is a rotor or drum, such as a brake rotor or brake drum that is mounted on a rotating shaft of a machine such as a lathe, forces acting on the shaft and workpiece during rotation of the shaft and workpiece may distort one or more planes and axes of rotation in connection with the rotor, and to exert a variety of angular and planar forces that may affect how accurately and quickly an operator of the lathe may work on the rotor. Forces and force vectors may cause harmonics and vibrations that may be transmitted to the shaft, rotor and other components of the lathe during rotation. Any nonuniform rotation of a rotor during a refinishing or resurfacing operation may cause a cutting tool brought in contact with a rotor to produce an inferior surface on a working area or surface of a rotor.
As indicated, during operation of a rotatable shaft on a machine for refinishing or resurfacing a rotor, forces including gravity, friction, velocity of rotation, and a variety of load forces may be applied during operation to bearings, driven shafts, turning spindles, retaining devices, locking nuts, and other components of driving machines and driven shafts (collectively, "machine members"). Similar forces may be induced in a workpiece such as a rotor. For example, circular rotation of shafts may give rise to centripetal force, a force that may be reacted to by centrifugal reaction. Angular velocity and angular acceleration of rotating workpieces subjected not only to varying velocities during operation, but also to differing loads or pressures, also may cause gyroscopic effects on rotating workpieces, such as a rotor, attached to a rotating machine member, such as a shaft, that may turn or rotate over a range of different speeds. Machine members, and workpieces attached to machine members, also may be subjected to significant loads about the geometric and rotational axes of a rotating workpiece. When two forces act on a rotatable shaft, spindle, pin, axle or similar rod or assembly (collectively, "shaft"), a torque may be formed whose vector along an x-axis may produce a rotation about the y-axis known as precession. Such rotation may generate significant angular velocities. All of the foregoing forces, phenomena, torque and related effects (collectively, "forces") may individually and collectively contribute to causing nonuniform rotation of a workpiece that has been attached to a rotating shaft on a machine such as brake lathe for working on a brake rotor.
In addition to such forces, angular accelerations and velocities may be present in connection with a rotating machine member, leading to unbalanced forces that induce high harmonics, chattering, and vibrations. In some but not all instances, if the speed of rotation of a shaft is slowly increased from rest, a speed may be achieved at which a deflection increases suddenly, a phenomenon known as "whirling." A shaft that is balanced will rotate around the center of gravity or axis of rotation of a shaft. If a shaft rotates at an angular velocity, however, the shaft may deflect a distance from the center of gravity or axis of rotation due to centripetal reaction. Rotation also may induce undamped free vibrations.
A machine used to refinish or resurface a brake rotor generally includes a driving motor, a driven or turning shaft, one or more retaining devices attached to the shaft for removably mounting a workpiece such as a brake rotor on the one or more retaining devices, and one or more cutting tools that may reciprocally engage a surface of a brake rotor to be machined, refinished or resurfaced. All of the foregoing forces and phenomena, and others, may contribute to nonuniform rotation of the shaft, and consequent nonuniform rotation of a rotor attached to a rotatable shaft. This is particularly true, but not exclusively, in machine members on which brake rotors are mounted for turning purposes, such as refinishing or resurfacing the brake rotor. A cutting tool brought into contact with a rotating rotor may also induce a variety of such forces and phenomena.
A variety of apparatus have been proposed to reduce or eliminate such forces and phenomena, seeking to enable a machine operator, including a brake lathe operator, to more effectively machine, refinish or resurface a rotating workpiece such as a brake rotor. Such apparatus, however, often include components that are complex, difficult to assemble, difficult to operate, and comparatively expensive. An example available in the market for securing a rotor to a rotatable shaft includes one or more jaws. The jaws, however, must be individually adjusted to hold a rotor in position on a lathe. A device such as a key must be used to adjust each jaw. Adjusting such an apparatus for varying sizes of rotors is time consuming, and therefore expensive. If an operator inadvertently leaves the key in the adjustable jaw and commences operation of the lathe, injury to the operator is likely.
Other apparatus for securing a rotor to a lathe customarily provide for a single flange that may be mounted on a shaft of a lathe. Another component is provided to press a rotor against the single flange. Conventionally, the flange is supposed to hold the rotor workpiece in a fixed vertical axis, while a cone shaped body is provided to help maintain the rotor work piece concentrically with respect to the shaft of the lather. Such apparatus, however, do not allow for a range of dimensional tolerances in the rotor, and often require frequent readjustment of the components assembled on a lathe if dimensions change from rotor to rotor to be machined. Cost of operation, therefore, is comparatively expensive.
The problem to be solved, therefore, is to provide an apparatus for securing a rotatable workpiece on a rotatable machine member, including a brake rotor on a brake rotor lathe, that reduces or substantially eliminates the effect of forces acting and reacting on the rotating workpiece and rotating shaft of the lathe. What also is needed is an apparatus for securing a workpiece, such as a rotor, to a rotatable shaft that reduces or eliminates the effect of forces on a rotating brake rotor, whether vented or unvented, to permit an operator to produce a more accurately and precisely machined, turned and resurfaced brake rotor.
One of the advantages of the novel apparatus for securing a rotor to a rotatable shaft, according to the present invention, is that the apparatus allows an operator of a lathe to produce a more accurately and precisely machined, turned and resurfaced brake rotor. Another advantage of the present invention is the ability of the apparatus to reduce or eliminate forces that otherwise tend to act and react on a rotating shaft and a rotating rotor during operation of a machine such as a lathe. The present invention also has the significant advantages of being simple to install and reposition.
Yet another advantage of the present invention is to provide a new and improved apparatus for securing a workpiece to a rotating machine member that may be easily and efficiently manufactured, yet is durable and of reliable construction. An even further advantage of the present invention is providing low cost of manufacture with regard to both materials and labor. The present invention is respectively easy to use and to practice, and cost effective for its intended purposes.
These advantages and other objects and features of such an apparatus for securing a workpiece to a machine member will become apparent to those skilled in the art when read in conjunction with the accompanying following description, drawing figures, and appended claims.